1. Field of the Invention
The invention relates to a novel filler-binder for tablets, a process for making tablets using said filler-binder and to tablets obtainable by said process.
2. Description of the Related Art
The production of tablets by direct compaction has for many years been a growing field in the pharmaceutical industry and other areas, such as tabletting of detergents. Many excipients with special advantages in the direct compaction process have been developed and applied in the past decades. Especially in the class of the filler-binders, many new excipients as well as many new physical forms of existing excipients have entered the market. For an overview of such excipients, reference is made to G. K. Bolhuis and Z. T. Chowhan, xe2x80x98Materials for direct compactionxe2x80x99, in xe2x80x98Pharmaceutical compaction technologyxe2x80x99, Eds. G. Alderborn and C. Nystrxc3x6m, Marcel Dekker, Inc., New York, 1996, pp. 419-500.
Because the ingredients for the tablets are usually only dry-mixed before compression, the characteristics and performance of the filler-binder are essential for the quality attributes of the final tablet. Typical examples of direct compaction filler-binders are the free flowing physical forms of lactose (spray dried or agglomerated), mannitol, microcrystalline cellulose, sorbitol, sucrose (compressible sugar), or inorganic salts. Each of these is available in different physical forms having their respective advantages in the direct compaction process.
To perform as a suitable filler-binder, an excipient should meet a number of requirements. The compactibility should be high to ensure that the tablet meets the usual requirements on crushing strength and friability. Further, a good flowability and good blending properties are needed in order to ensure mass (and content) uniformity of the tablet. Inertness of the excipient is necessary in order to avoid interaction with the drug or other active substance present in the tablet, or with any other excipient. A filler-binder should moreover be stable during storage under different conditions. Both as raw material and when present in the tablet, its physico-chemical properties should remain substantially unchanged over time. Also, a filler-binder should be non-toxic and accepted by regulatory authorities, preferably it is described in pharmacopeia. In addition, a filler-binder preferably has a high batch to batch reproducibility with respect to the physico-chemical quality of the product. Finally, other requirements may relate to the effect of the filler-binder on the disintegration and drug release, price and the world-wide availability of the material.
A great disadvantage of the known filler-binders is that they are very sensitive to the presence of lubricants, particularly when tablets are produced using high speed tabletting machines as is being done in the pharmaceutical industry.
Lubricants are substances incorporated into tablets for prevention of adhesion between the tablet (to be) formed and the equipment used for its formation, such as punches and dies or other parts of a press used for compaction, and the like. Examples of compounds that are regularly used as lubricant in this respect are fatty substances, such as magnesium stearate, sodium stearylfumarate, glycerylbehenate, glyceryl monostearate, calcium stearate, hydrogenated vegetable oil, polyethylene glycol, talc, and zinc stearate. It is believed that the lubricant partially or completely coats the filler-binder particles. Thus, due to the presence of the lubricant, particularly after compaction has been carried out, the surface area of the filler-binder particles that is in direct contact with other filler-binder particles is significantly reduced, leading to a significantly reduced binding capacity of the filler-binder. This effect is particularly apparent in the case of filler-binders that show plastic deformation upon compaction. However, said effect also occurs, although to a lesser degree, with filler-binders that are brittle and fragment upon compaction.
The present invention aims to provide a filler-binder for tablets that shows a reduced lubricant sensitivity when compared with the prior art filler-binders. Of course, the filler-binders should meet many, if not all, of the criteria mentioned above, so that it is suitable for use as a filler-binder in tablets.
Surprisingly, it has now been found that when a filler-binder has a specific morphology, its sensitivity in binding capacity to a lubricant in a tablet is significantly reduced. The desired effect is achieved when the filler-binder consists of particles, which are hollow. Thus, the invention relates to a filler-binder for a tablet in the form of hollow particles.